It has been a long-standing goal in the art to provide as high a degree of automation as possible in the application of protective coatings as well as decorative stripes and markings on a variety of commercial goods. One such example is the automated painting of automobiles through the use of a plurality of robots in sequential work stations. While the application of a protective coating onto an automobile has been substantially automated, attempts to automate the decorative aspects of automobile painting such as pinstriping and monogramming have been beset with problems. The present invention seeks to overcome problems now inherent in many painting applications through the disclosure of a technique for the application and cure of photosensitive paints. While automobiles provide an excellent example of the type of objects which can readily lend themselves to the technique of this invention, it is to be appreciated that any type of product such as an appliance, furniture or even a toy can be painted with and decoratively marked by the technique of this invention.
A contemporary practice in the manufacture of automobiles is the use of decorative trim along various body portions thereof. For example, it is a relatively common practice to provide pinstriping on automobiles. Pinstriping is a process whereby narrow lines of paint for highlighting are placed on certain locations of the car body. In automobile assembly plants, pinstriping is a truly manual process. Generally, there are two methods for the application of pinstriping to automobiles. The use of one application over the other is typically dependent upon the price range and the class of the automobile being manufactured. One technique for pinstriping uses a plastic film which is not unlike a roll of adhesive tape. This plastic film is manually applied to the desired body portion of the automobile. A second technique for more expensive vehicles requires the manual application of paint onto the vehicle. Automobiles on a production line are individually striped at a given work station. Quite often, such work stations cannot handle the volume of automobiles passing therethrough and buffer overflow lines exist whereby a vehicle can be removed from the vehicle production line for pinstriping and then later returned to the production line. The hand-painting process usually requires the vacuum attachment of an alignment guide to the automobile at a desired location. A worker manually manipulates a tool consisting of a knurled wheel with a paint feeder tube along the alignment guide to form the stripe. Obviously, multiple stripes require multiple passes with different tools depending upon both the width and the complexity of the pinstriping design as well as the contour of the automobile body. Because the rollers tend to skid, the tapered ends of a decorative pinstripe are very difficult to form. The alignment tool is difficult to handle and at times can cause scratches on the painted surface of the automobile. The present manual process is extremely labor intensive and should lend itself to automation.
Attempts have been made to automate the heretofore manual paint striping process by simply replacing a workman with a robot. However, nearly all of the problems identified above remained and a greater problem of substantial body damage to the subject automobile due to a misguided robot was also present. It is felt that in order to solve the above-described problems and difficulties associated with pinstriping and detailing of automobiles, an automated, non-contact process is needed.
In order to provide an automatic paint detailer which would eliminate the problems described above, one embodiment of the present system utilizes ultraviolet light radiation curing paint. The existence of pigmented polymerized binders which can be cured by ultraviolet or laser light have been known in the art. One example is taught in U.S. Pat. No. 3,847,771 to McGinniss while other paints which are curable by light having a wavelength in the ultraviolet range are known from U.S. Pat. Nos. 3,364,387; 4,052,280; 4,107,353; and 4,351,708; and from Rybny et al., "New Developments in Ultraviolet Curable Coatings Technology", the contents of which documents are incorporated by reference herein.
It is also known to apply paint to an automobile body by a robotic arm. For example, U.S. Pat. No. 4,539,932 to Vecellio teaches a robotic painting system for electrostatically painting an automobile body that includes a paint module adapted to maintain the automobile body in a stationary position relative to at least two painting robots. Each of the painting robots carries an atomizing device and provides programmed movement about five control axes at a speed which prevents the cone-shaped pattern of atomized paint particles from being distorted due to any gyroscopic affect developed by the atomizing device as it is moved about the control axes. Another example of a vehicle body painting robot can be found in U.S. Pat. No. 4,498,414 to Kiba et al. This patent teaches a vehicle body painting robot for automatically coating a paint on vehicle bodies which are transferred along a conveyor line. The robot includes an arm which is supported on a pedestal rotatably in both vertical and horizontal planes, and a paint applicator for spraying the paint towards a vehicle body delivered to a coating booth. Both of the aforesaid patents are incorporated herein by reference.
It is therefore an object of the present invention to provide a method and an apparatus for the automatic paint detailing of an automobile.
It is a further object of this invention to provide a technique and apparatus in which a robotic arm manipulates a UV light source to direct the light over an area of uncured paint.
It is yet another object of this invention to provide a method and apparatus whereby unique designs and trim detailing such as for example pinstriping and monogramming of vehicles, appliances, furniture and miscellaneous items can be accomplished utilizing a UV-cured paint.
It is still another object of this invention to provide a work station for use in combination with an automobile assembly line for the application of paint detailing and trim to an automobile.
It is another object of the invention to provide a laser marking system of the type employing a stencil whereby a plurality of stencil patterns can be selectively brought into the path of the laser beam for marking the surface of an article with a selected pattern.
It is a further object of the invention to provide a method of marking the surface of an article employing a laser marking system in combination with a paint which is curable upon being irradiated with a laser beam.